阅读说明：本技术 一种双层五边形电极的薄膜体声波谐振器 (Film bulk acoustic resonator with double-layer pentagonal electrode ) 是由 李国强 刘鑫尧 衣新燕 张铁林 赵利帅 刘红斌 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种双层五边形电极的薄膜体声波谐振器。所述薄膜体声波谐振器从上至下包括顶电极、压电层、底电极构成的压电振荡堆结构,以及支撑层(连接层)和衬底。本发明所述的顶电极由内外两层五边形构成,由同一圆周的内外界五边形经一定角度旋转获得。本发明所述的顶电极外层厚度高于内层五边形厚度,在边缘处形成台阶边框,其余位置均为平面,且内外五边形任意两边均不平行,从而形成非对称图形,使得横向寄生的声波产生衰减和分散。本发明通过设计电极层的形状尺寸,在不增加工艺步骤的前提上抑制谐振器的横向剪切波,提高谐振器的Q值,优化薄膜体声波谐振器谐振特性。(The invention discloses a film bulk acoustic resonator with double-layer pentagonal electrodes. The film bulk acoustic resonator comprises a piezoelectric oscillation stack structure formed by a top electrode, a piezoelectric layer and a bottom electrode, a supporting layer (a connecting layer) and a substrate from top to bottom. The top electrode is formed by an inner layer of pentagon and an outer layer of pentagon, and is obtained by rotating the inner pentagon and the outer pentagon of the same circumference at a certain angle. The thickness of the outer layer of the top electrode is higher than that of the inner layer of the pentagon, a step frame is formed at the edge, the rest positions are planes, and any two sides of the inner pentagon and the outer pentagon are not parallel, so that an asymmetric pattern is formed, and transverse parasitic sound waves are attenuated and dispersed. According to the invention, by designing the shape and size of the electrode layer, the transverse shear wave of the resonator is inhibited on the premise of not increasing the process steps, the Q value of the resonator is improved, and the resonance characteristic of the film bulk acoustic resonator is optimized.)

1. A film bulk acoustic resonator with double-layer pentagonal electrodes comprises a piezoelectric oscillation stack structure, a supporting layer and a substrate, wherein the piezoelectric oscillation stack structure is composed of a top electrode, a piezoelectric layer and a bottom electrode from top to bottom; the method is characterized in that: the outline of the piezoelectric oscillation stack structure is a pentagonal graph with an inner circle and an outer circle, and any two sides of the pentagonal graph are not parallel; an acoustic reflection interface is arranged on the substrate, the piezoelectric oscillation stack structure is arranged on the acoustic reflection interface, and the effective area of the piezoelectric oscillation stack structure is larger than that of the acoustic reflection interface.

2. The film bulk acoustic resonator with the double-layer pentagonal electrode as claimed in claim 1, wherein the top electrode is formed by inner and outer circles of pentagonal electrodes, and the two circles of pentagonal electrodes are internally tangent pentagons and externally tangent pentagons with the same radius circumference.

3. The film bulk acoustic resonator with the double-layer pentagonal electrode as claimed in claim 2, wherein, from a top view, an included angle is formed between the inner and outer pentagonal electrodes of the top electrode, the included angle is in a range of 0-360 degrees and is not equal to n × 36 degrees, n is an integer and n has a value in a range of 1-9.

4. The film bulk acoustic resonator of a double-layer pentagonal electrode as claimed in claim 2, wherein the thickness of the inner pentagonal electrode of the top electrode is 100-300nm, and the thickness of the outer pentagonal electrode of the top electrode is 300-1200 nm.

5. The film bulk acoustic resonator with the double-layer pentagonal electrode as claimed in claim 2, wherein the inner and outer pentagonal electrodes of the top electrode are made of the same material, and the top electrode is made of more than one of molybdenum, tungsten, gold, aluminum, silver and titanium.

6. The double-layer pentagonal-electrode thin-film bulk acoustic resonator of claim 1, wherein the substrate is one of a high-resistance silicon, sapphire substrate or SOI substrate.

7. The double-layer pentagonal-electrode thin-film bulk acoustic resonator of claim 1, wherein the top and bottom electrodes are both metal thin films.

8. The film bulk acoustic resonator with the double-layer pentagonal electrode as claimed in claim 1, wherein the piezoelectric layer is a film material with piezoelectric effect, and the support layer is a physical support layer or a metal bonding layer; the physical supporting layer is an insulating film; the physical support layer is silicon nitride or silicon dioxide.

9. The film bulk acoustic resonator with the double-layer pentagonal electrode as claimed in claim 8, wherein the piezoelectric layer is a film material with a piezoelectric effect, and the piezoelectric layers are PZT, AlN, GaN, ZnO, CdS and L iNbO₃One or more of them.

10. The double-layer pentagonal-electrode thin film bulk acoustic resonator according to claim 1, wherein the acoustic reflection interface is an air cavity or a Bragg reflection layer formed by overlapping high and low acoustic impedances.

Technical Field

The invention relates to the technical field of bulk acoustic wave resonators, in particular to a film bulk acoustic wave resonator with double-layer pentagonal electrodes.

Background

With the rapid development of microwave wireless technology, in the current mobile communication terminal, the sound wave filtering technology is very important due to its excellent high-frequency use performance. The further development of communication technology puts new requirements on integration, miniaturization, high performance, low cost and the like on a filter working in a radio frequency band. The Film Bulk Acoustic Resonator (FBAR) has excellent performances such as small volume, low loss, large power capacity, integration and the like, and has wide application prospects in the fields of sensing, measurement and control, communication and the like.

The core structure of the film bulk acoustic resonator is a piezoelectric oscillation stack structure formed by electrodes, a piezoelectric layer and electrodes, and the working principle is that when electric signals alternating in the world are arranged on the electrodes at two ends, the electric signals are converted into mechanical signals due to the inverse piezoelectric effect of materials, the mechanical signals are transmitted in the film in the form of sound waves, when the wavelength and the thickness of the sound waves in the vertical direction meet certain conditions, standing waves are generated, the energy loss is minimum at the moment, and finally the sound signals are converted into the electric signals through the piezoelectric effect to carry out frequency selection. The most important part of the bulk acoustic wave resonator is piezoelectricity of a piezoelectric oscillation stack structure, and the high quality factor (Q value) enables the bulk acoustic wave resonator to show excellent suppression and insertion loss performance even in the places where the frequency band is crowded and the edges of the pass band are tight. The influence of the transverse parasitic of the film bulk acoustic resonator on the Q value is more and more obvious along with the gradually increasing use frequency band. Suppressing lateral parasitics can further improve the high frequency performance and Q-value of the resonator.

The increasing development of radio frequency microwave technology puts more stringent requirements on the working conditions of radio frequency devices. The working frequency is continuously improved, and simultaneously, higher requirements on the size, the service performance, the stability and the integration of the device are also met. The Film Bulk Acoustic Resonator (FBAR) has excellent performances such as small volume, low loss, large power capacity, integration and the like, and has wide application prospects in the fields of sensing, measurement and control, communication and the like.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a film bulk acoustic resonator with double-layer pentagonal electrodes.

The invention provides a film bulk acoustic resonator with double-layer pentagonal electrodes, which is an improved film bulk acoustic resonator with double-layer pentagonal electrodes. The invention restrains the lateral parasitic effect generated when the FBAR device is vertically excited by the design of the electrode shape and the step, and the FBAR adopting the electrode can have a higher Q value and avoid the generation of the spurious wave. On the basis of not additionally increasing process steps, the transverse wave is restrained, and the manufacturing cost is controlled.

The purpose of the invention is realized by at least one of the following technical solutions.

The invention provides a film bulk acoustic resonator with double-layer pentagonal electrodes, which comprises a piezoelectric oscillation stack structure, a supporting layer (a connecting layer) and a substrate, wherein the piezoelectric oscillation stack structure is composed of a top electrode, a piezoelectric layer and a bottom electrode from top to bottom; the outline of the piezoelectric oscillation stack structure is a pentagonal graph with an inner circle and an outer circle, and any two sides of the pentagonal graph are not parallel; an acoustic reflection interface is arranged on the substrate, the piezoelectric oscillation stack structure is arranged on the acoustic reflection interface, and the effective area of the piezoelectric oscillation stack structure is larger than that of the acoustic reflection interface.

Furthermore, the top electrode is composed of an inner circle of pentagonal electrodes and an outer circle of pentagonal electrodes, and the two circles of pentagonal electrodes are internally tangent pentagons and externally tangent pentagons with the same radius circumference.

Furthermore, from a top view, an included angle is formed between the inner and outer circles of the pentagonal electrodes of the top electrode, the degree range of the included angle is 0-360 degrees and is not equal to n × 36 degrees, n is an integer and the value range of n is 1-9.

Furthermore, the thickness of the inner-ring pentagonal electrode of the top electrode is 100-300nm, and the thickness of the outer-ring pentagonal electrode of the top electrode is 300-1200 nm.

Furthermore, the inner and outer pentagons of the top electrode are made of the same material, and the top electrode is made of one or more of molybdenum, tungsten, gold, aluminum, silver, titanium and the like.

Further, the substrate is one of high-resistance silicon, lithium niobate, a sapphire substrate or an SOI substrate. The substrate is suitable for a film bulk acoustic resonator.

Further, the top electrode and the bottom electrode are both metal films.

Further, the piezoelectric layer is a thin film material with a piezoelectric effect, and the support layer is a physical support layer or a metal bonding layer. The physical support layer is an insulating film of silicon nitride, silicon dioxide or the like. The metal bonding layer is made of intermetallic compounds such as Au/Sn, Au/Au, Ni/Sn and the like.

Furthermore, the piezoelectric layer is a thin film material with piezoelectric effect, and the piezoelectric layer is PZT, AlN, GaN, ZnO, CdS and L iNbO₃One or more of them.

Further, the acoustic reflection interface is an air cavity or a Bragg reflection layer formed by overlapping high and low acoustic impedances.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the invention utilizes the design of the geometric shape of the electrode to strengthen the reflection of longitudinal wave in the film bulk acoustic resonator and reduce the loss of shear wave; the designed electrode structure is formed by an inner layer of pentagon and an outer layer of pentagon which rotate at a certain angle, wherein any two sides are not parallel, so that an asymmetric geometric figure is formed, standing waves cannot be generated by transverse sound waves generated by excitation, and the propagation direction and the phase of the transverse reflected sound waves do not meet the oscillation condition, so that the transverse reflected sound waves are dispersed and attenuated; the steps are arranged on the longitudinal dimension to inhibit the parasitic effect, and the double-pentagonal pattern is arranged on the transverse dimension to inhibit the parasitic effect, so that transverse standing waves are further reduced; the manufacturing cost of the device is controlled without increasing the process steps, so that the performance of the device is further improved.

Drawings

Fig. 1 is a top view of a film bulk acoustic resonator with a double-layer pentagonal electrode according to an embodiment of the present invention;

fig. 2 is a cross-sectional view of a film bulk acoustic resonator with a first double-layer pentagonal electrode in embodiment 1 of the present invention;

fig. 3 is a cross-sectional view of a film bulk acoustic resonator having a second double-layer pentagonal electrode according to embodiment 2 of the present invention;

fig. 4 is a cross-sectional view of a film bulk acoustic resonator with a third double-layer pentagonal electrode in embodiment 3 of the present invention.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.